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Discussion Starter #1
Greetings one and all.

It's June; so it's time to drag out the Snowblower's and get them tuned and ready.

One project I'm working on is a Toro 521 that I am looking to do a motor swap on. Usually, I read in posts, folks have to get an adapter to increase the thickness of the new motors shaft to match the old pulleys, I need to go in the other direction: The shaft for the motor I would like to use is thicker than the original Tecumseh motor, so I need to get some pulleys to fit.

The Tecumseh 5hp has a shaft that looks to be about 3/4" and the the Chinese motor I have has what appears to be 7/8's shaft.

The replacement motor is a 208cc from a Troy-Bilt single stage blower, made around 2008, it say's MTD on a label but I don't know who made it for them.

Can anyone hold my hand, be gentile, and point me towards the kind of pulleys I would need? Does Tractor Supply carry anything along the lines of what I would need? Other than shaft size what else should I look at, to keep it close to stock as possible.

Thanks in advance

K
 

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you may want to double check your measurements. if that 208cc is anything like the 1 i plan on putting on my snowblower it should have a 1" output shaft. tractor supply should have pulleys. you could also look for someone parting out a snowblower with 8+hp engine on it. the 8hp and larger generally have a 1" output shaft also.
 

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Discussion Starter #4

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you may want to double check your measurements. if that 208cc is anything like the 1 i plan on putting on my snowblower it should have a 1" output shaft. tractor supply should have pulleys. you could also look for someone parting out a snowblower with 8+hp engine on it. the 8hp and larger generally have a 1" output shaft also.
I will look into that. My measurement was taken by closing an adjustable wrench on the shaft(s) and then measuring the gap. I expected 1" but it appeared to be only 7/8. Thinking about it now, I believe I may also have a pulley from a 8hp Tecumseh somewhere. If that does fit it sure would be sweet.

Thanks for the tips.

K
 

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Discussion Starter #7
7/8" is just an oddball size that i think you only see on smaller lawnmowers engines. the bigger lawnmowers usually run a 1" output shaft
I double checked this morning and it does appear to be a 7/8 shaft. I did the crescent wrench deal again, this time including the 8hp Tec motor I have as well, and the shaft on the 8hp motor is thicker than this 208cc I am trying to use.

I'm hunting now for pulley's, the original seems to be about 2 1/2 OD, and, if worse comes to worst, if I cant find a pulley for a 7/8 shaft I will look for one for a 1" shaft and use a sleeve to adapt the shaft to the new pulley(s).

K
 

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Seems MTD likes to use 7/8 shafts on the the Troy Bilt line as I have a 179cc from a Troy Bilt and it IS a 7/8 shaft. Another member here had done exactly what you are and I am pretty sure he got one from Tractor supply.
 

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Discussion Starter #11
you might be able to reuse the 1 pulley on the new engine. it looks like there is a spacer between the 2 half's.

Perhaps, but potentially not without some serious reworking of the pulley. The pulley is spit in the valley, my guess is to facilitate the easy replacement of a belt, which is fine, but the back half has a very long shoulder that might have to be modified in order to get a second pulley on the shaft.

There is a second spacer on the shaft, about a inch long, and if the second pulley I need is only that wide I would perhaps be able to then make it work, but my guess would be that I would instead end up having to reduce the shoulder on the original pulley; easier to find two matching pulleys that fit the shaft I think.

Thanks for the input.

K
 

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Discussion Starter #17
How does the "spacer" accommodate the key ?
Yes, it is like Crazywolf said.

The spacer itself has no key and would just spin freely if it were not pressed between the shoulder of the pulley and a shoulder on the shaft. Interestingly the shaft beyond that shoulder is 1 inch; it would have been nice if they just left the whole shaft that way but, from an engineering perspective, it does simplify the assembly process for the purpose it was intended, keeping things aligned and in place.
 

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Aren't all of these Chinese Engines "metric" . . . . so that so that you'll only be able to approximate something sized in imperial Inches ?

At any rate, I thought the OP's problem was having a new Chinese Engine whose CrankShaft was larger than that of the retiring engine, so the inside diameter of the Pulley would have to be enlarged to fit over it . . . . so I don't see how a sleeve will be helping in that regard ?
 

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Aren't all of these Chinese Engines "metric" . . . . so that so that you'll only be able to approximate something sized in imperial Inches ?

At any rate, I thought the OP's problem was having a new Chinese Engine whose CrankShaft was larger than that of the retiring engine, so the inside diameter of the Pulley would have to be enlarged to fit over it . . . . so I don't see how a sleeve will be helping in that regard ?
The popular HF Predator has a 3/4 shaft (19.1 mm) diameter.
The suggestion for a sleeve was my mistake, I didn't read the post correctly and had things backward.
 
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